1. Field of the Invention
The invention relates to a polishing pad, a polishing method, and a polishing system. More particularly, the invention relates to a polishing pad, a polishing method, and a polishing system enabling a slurry to have a different flow distribution.
2. Description of Related Art
With the progress of the industries, planarization processes are often adopted as processes for manufacturing various devices. Chemical mechanical polishing (CMP) processes are often used in the planarization processes in the industries. General speaking, the chemical mechanical polishing processes are performed by supplying a slurry which has chemical mixtures on a polishing pad, applying a pressure on the article to be polished to press it on the polishing pad, and providing a relative motion between the article and the polishing pad. Through the mechanical friction generated by the relative motion and the chemical effects of the slurry, a portion of the surface layer of the article is removed to make the surface flat and smooth so as to achieve planarization.
Conventional polishing pad includes a polishing layer and a plurality of circular grooves disposed in the polishing layer. The circular grooves are disposed in a concentric arrangement in the polishing layer, for example. During the polishing process, a portion of the slurry flows outward in a radial direction from the circular grooves to the surface of the polishing layer due to the centrifugal force generated from the rotation of the polishing pad. Nevertheless, most of the slurry is still contained in the circular grooves and only a small portion flows to the surface of the polishing layer.
Another conventional polishing pad includes a polishing layer and a plurality of edge extending grooves disposed in the polishing layer. The edge extending grooves, for example, are disposed in a radial or spiral arrangement in the polishing layer and extend to an edge of the polishing layer. In the polishing process, the relative motion between a carrier ring in the polishing system and the edge extending grooves causes most of the slurry to be squeezed over the edge of the polishing layer by the carrier ring and then flows out, while only a small portion of the slurry flows between the surface of the polishing layer and the substrate.
During the polishing process, a flow distribution of the slurry affects polishing characteristics. Therefore, it is necessary to provide polishing pads which have different flow distributions for industry in response to the requirements of various polishing processes.